Smart City technologies emerge as a potential solution to tackle common problems in large urban centers by using city resources efficiently and providing quality services for citizens. Despite the various advances in middleware technologies to support future smart cities, there are yet no widely accepted platforms. Most of the existing solutions do not provide the required flexibility to be shared across cities. Moreover, the extensive use and development of non-open-source software leads to interoperability issues and limits the collaboration among R&D groups. Our research explores the use of a microservices architecture to address key practical challenges in smart city platforms. More specifically, we are concerned with the impact of microservices on addressing the key non-functional requirements to enable the development of smart cities such as supporting different scalability demands and providing a flexible architecture which can easily evolve over time. To this end, we are developing InterSCity, a microservice-based open source smart city platform that aims at supporting the development of sophisticated, cross- domain applications and services. Our early experience shows that microservices can be properly used as building blocks to achieve a loosely coupled, flexible architecture. Experimental results point towards the applicability of our approach in the context of smart cities since the platform can support multiple scalability demands. We expect to enable collaborative, novel smart city research, development, and deployment initiatives through the InterSCity platform. The full validation of the platform will be conducted using different smart city scenarios and workloads. Future work comprises the ongoing design and development effort on data processing services as well as more comprehensive evaluation of the proposed platform through scalability experiments. / As tecnologias de Cidades Inteligentes surgem como uma potencial solução para lidar com problemas comuns em grandes centros urbanos, utilizando os recursos da cidade de maneira eficiente e fornecendo serviços de qualidade para os cidadãos. Apesar dos vários avanços nas tecnologias de middleware para suporte às cidades inteligentes do futuro, ainda não existem plataformas amplamente aceitas. A maioria das soluções existentes não oferece a flexibilidade necessária para ser compartilhada entre as cidades. Além disso, o vasto uso e desenvolvimento de software proprietário levam a problemas de interoperabilidade e limitam a colaboração entre grupos de P&D. Nesta dissertação, exploramos uso de uma arquitetura de microsserviços para abordar os principais desafios práticos em plataformas de cidades inteligentes. Mais especificamente, estamos preocupados com o impacto dos microsserviços sobre requisitos não-funcionais para permitir o desenvolvimento de cidades inteligentes, tais como o suporte a diferentes demandas de escalabilidade e o fornecimento de uma arquitetura flexível que pode evoluir facilmente. Para esse fim, criamos a InterSCity, uma plataforma para cidades inteligentes de código aberto baseada em microsserviços que visa apoiar o desenvolvimento de aplicativos e serviços sofisticados em múltiplos domínios. Nossa experiência inicial mostra que os microsserviços podem ser usados adequadamente como blocos de construção para obter uma arquitetura flexível e fracamente acoplada. Resultados experimentais apontam para a aplicabilidade de nossa abordagem no contexto de cidades inteligentes, já que a plataforma pode suportar diferentes demandas de escalabilidade. Esperamos permitir pesquisas colaborativas e inovadoras em cidades inteligentes, assim como o desenvolvimento e iniciativas de implantações reais através da plataforma InterSCity. A validação completa da plataforma será realizada usando diferentes cenários de cidades inteligentes e cargas de trabalho. Os trabalhos futuros compreendem o esforço contínuo de projetar e desenvolver novos serviços de processamento de dados, bem como a realização de avaliações mais abrangentes da plataforma proposta por meio de experimentos de escalabilidade.

Veículos Aéreos não tripulados (VANTs) vêm sendo cada vez mais utilizados em diversos países, tanto na área militar como na civil. O cenário considerado nesse estudo é o de um VANT realizando captura de vídeo em tempo real, transmitindo-o a uma base terrestre por meio de rede sem fio. O problema consiste no fato de não ser possível garantir uma taxa de transmissão contínua, com banda estável. Isso ocorre devido a fatores como a velocidade da aeronave (da ordem centenas de km/h), irregularidades de terreno (impedindo a linha de visada do enlace de transmissão), ou do clima, como tempestades que podem interferir na transmissão da RF. Por fim, os movimentos que o VANT pode realizar no vôo (Rolagem, Arfagem ou Guinada) podem prejudicar a disponibilidade do link. Dessa forma, é necessário que seja realizada adaptação de vídeo de acordo com a banda disponível. Assim, quando a qualidade do enlace for degradada, deverá ser realizada uma redução no tamanho do vídeo, evitando a interrupção na transmissão. Por outro lado, a adaptação também deverá fazer com que a banda disponível seja utilizada, evitando o envio de vídeos com qualidade inferior à que seria possível para determinado valor de largura de banda. Nesse trabalho será considerada a faixa de valores de largura de banda de 8 Mbps até zero. Para realizar a adaptação será utilizado o padrão H.264/AVC com codificação escalável / Unmanned Aerial Vehicles (UAVs) are being increasingly used in several countries, both in the military and civilian areas. In this study we consider an UAV equipped with a camera, capturing video for a real-time transmission to a ground-base using wireless network. The problem is that its not possible to ensure a continuous transmission rate, with stable bandwidth. That occurs due to factors like the speed of the aircraft, irregularities of terrain, or the weather (as storms, heat and fog, for instance, can interfere with RF transmission). Finally, the movements that the UAV can perform in flight (Roll, pitch and yaw) can impair link availability. Thus, it is necessary to perform an adaptation of video according to the available bandwidth. When the link quality is degraded, a reduction in the resolution of the video must be performed , avoiding interruption of the transmission. Additionally, adaptation must also provide that all the available bandwidth is used, avoiding sending the video with lower quality that would be possible for a given value bandwidth. In this work we propose a system which can vary the total amount of data being transmitted, by adjusting the compression parameters of the video. We manage to produce a system which uses the range from 8 Mbps up to zero. We use the H.264/AVC Codec, with scalable video coding

This thesis deals with an approach to monitor the integrity and composition of cargo wagons withthe help of Wireless Sensor Network (WSN). The WSN is to be fully automated that does notneed any human intervention for gathering information about the composition and integrity ofcargo trains, which are the most necessary factors for Cargo Logistics. The nodes are deployed inevery wagon along with the master node in the main locomotive. The master node in thelocomotive gets the information from the slave nodes placed in the cargo wagons in successivesessions. If there are any unexpected changes in the composition of the wagon, theacknowledgments to the locomotive will be terminated. This approach mainly focuses ondesigning energy-efficient as well as cost-efficient WSN. The designed WSN can accommodateto changes, which are caused by external conditions. The designed approach is also scalable. TheWSN is designed with the usage of Zigbee mesh protocol with Arduino Microcontroller as thebrain of the system that is validated and verified in the indoor, imitating the railway environment.

Distributed ledger technology (DLT) stands to benefit industries such as financial services with transparency and censorship resistance. DLT systems need to be scalable to handle mass user adoption. Mass user adoption is required to demonstrate the true value of DLT. This dissertation first analyses scalability in ethereum and EOS. Currently, ethereum 1.0 uses proof of work (PoW) and handles only 14 transactions per second (tps) compared to Visa's peak 47 000 tps. Ethereum 2.0, known as Serenity, introduces sharding, proof of stake (Casper), plasma and state channels in and effort to scale the system. EOS uses a delegated proof of stake (DPoS) protocol, where 21 super-nodes, termed ‘block producers' (BPs), facilitate consensus, bringing about significant scalability improvements (4000 tps). The trade-off is decentralisation. EOS is not sufficiently decentralised because the BPs yield significant power, but are not diverse. This dissertation conducts an empirical analysis using unsupervised machine learning to show that there is a high probability collusion is occurring between certain BPs. It then suggests possible protocol alterations such as inverse vote weighting that could curb adverse voting behaviour in DPoS. It further analyses whether universities are suitable BP's before mapping out required steps for universities to become block producers (leading to improved decentralisation in EOS)

Syftet med det här arbetet är att undersöka hur överföringstid skiljer sig i förhållande tillskalbarhet mellan två back-endlösningar i LoRaWAN. Lösningarna är Node-RED ochChirpstack. Studien genomförs med hjälp av metoderna experiment och fallstudie. Iexperimentet utfördes ett t-test för att svara på om nollhypotesen kan förkastas eller inte.Resultatet visar att nollhypotesen inte kunde förkastas, och att det inte är någon skillnadi skalbarhet. Bortsett från t-testet visar resultaten att Chirpstack skalar sämre änNode-RED vid fyra eller fler tillagda enheter. Slutsatsen är däremot att skillnaden ärtillräckligt liten för att bedömas obetydlig för val av back-endlösning. Studien ärbegränsad till sju uppkopplade LoRa-enheter. / The purpose of this study is to investigate how transfer time differs in relation toscalability between two back-end solutions in LoRaWAN. The solutions are Node-REDand Chirpstack. The study is carried out using the methods experiment and case study.In the experiment, a t-test was performed to answer whether the null hypothesis can berejected or not. The results show that the null hypothesis could not be rejected, and thatthere is no difference in scalability. Apart from the t-test, the results show that Chirpstackscales worse than Node-RED at four or more added LoRa-units. The conclusion,however, is that the difference is small enough to be considered insignificant for thechoice of back-end solution. The study is limited to seven connected LoRa units.

Tato diplomová práce se zabývá návrhem a implementací rozšíření pro UnifiedPush Server, které serveru umožní přistupovat k nerelační databázi MongoDB a využívá potenciál horiznotální škálovatelnosti neralačních databází. Součástí práce je i návrh výkonnostních testů a porovnání výkonu při behu na jednom a vícero uzlích, návrh migračního scénáře z MySQL na MongoDB, identifikace úzkých míst. Aplikace je implementována v jazyce Java a využívá Java Persistence API pro přístup k databázím. Pro přístup k nerelačním databázím používá implementaci standardu JPA Hibernate OGM.

abstract: Virtualization technologies are widely used in modern computing systems to deliver shared resources to heterogeneous applications. Virtual Machines (VMs) are the basic building blocks for Infrastructure as a Service (IaaS), and containers are widely used to provide Platform as a Service (PaaS). Although it is generally believed that containers have less overhead than VMs, an important tradeoff which has not been thoroughly studied is the effectiveness of performance isolation, i.e., to what extent the virtualization technology prevents the applications from affecting each other’s performance when they share the resources using separate VMs or containers. Such isolation is critical to provide performance guarantees for applications consolidated using VMs or containers. This paper provides a comprehensive study on the performance isolation for three widely used virtualization technologies, full virtualization, para-virtualization, and operating system level virtualization, using Kernel-based Virtual Machine (KVM), Xen, and Docker containers as the representative implementations of these technologies. The results show that containers generally have less performance loss (up to 69% and 41% compared to KVM and Xen in network latency experiments, respectively) and better scalability (up to 83.3% and 64.6% faster compared to KVM and Xen when increasing number of VMs/containers to 64, respectively), but they also suffer from much worse isolation (up to 111.8% and 104.92% slowdown compared to KVM and Xen when adding disk stress test in TeraSort experiments under full usage (FU) scenario, respectively). The resource reservation tools help virtualization technologies achieve better performance (up to 85.9% better disk performance in TeraSort under FU scenario), but cannot help them avoid all impacts. / Dissertation/Thesis / Masters Thesis Computer Science 2019

Afin de répondre aux besoins de la 5G, nous évaluons plusieurs visions du cœur de réseau. Nous comparons les performances des visions en mesurant le temps nécessaire pour établir le service pour l’utilisateur. De plus, nous proposons dans cette thèse un algorithme basé sur la théorie du contrôle permettant d’équilibrer la charge entre les instances AMF, et d’augmenter ou de diminuer le nombre d’instances AMF en fonction de la charge du réseau. En outre, nous proposons un nouveau mécanisme pour adapter les ressources du réseau cœur 5G en anticipant les évolutions, de la charge de trafic, grâce à des prédictions via des approches de machine learning. Enfin, nous proposons une solution pour généraliser les réseaux de neurones tout en accélérant le processus. / In order to fulfil the needs of 5G, we evaluate, using a testbed, multiple visions of core networks. We compare the performances of the visions in terms of the time needed to create the user data plane. In addition, we provide an algorithm based on Control Theory allowing to equilibrate the load on the AMF instances, and to scale out or in the AMF instances depending on the network load. Also, we propose a novel mechanism to scale 5G core network resources by anticipating traffic load changes through forecasting via deep learning approaches. Finally, we propose a novel solution to generalize neural networks while accelerating the learning process.

The purpose of this thesis was to find approaches solving major performance and scalability issues for Topic Maps-related data access and the merging process. Especially regarding the management of multiple, heterogeneous topic maps with different sizes and structures. Hence the scope of the research was mainly focused on the Maiana web application with its underlying MaJorToM and TMQL4J back-end.

As more industrial processes, transportation and appliances have been automated or equipped with some level of artificial intelligence, the number and scale of interconnected systems has grown in the recent past. This is a development which can be expected to continue and therefore the research in performance of interconnected systems and networks is growing. Due to increased automation and sheer scale of networks, dynamically scaling networks is an increasing field and research into scalable performance measures is advancing. Recently, the notion gamma-robustness, a scalable network performance measure, was introduced as a measurement of interconnected systems robustness with respect to external disturbances. This thesis aims to investigate how the distribution of control effort and cost, within interconnected system, affects network performance, measured with gamma-robustness. Further, we introduce a notion of fairness and a measurement of unfairness in order to quantify the distribution of network properties and performance. With these in place, we also present distributed algorithms with which the distribution of control effort can be controlled in order to achieve a desired network performance. We close with some examples to show the strengths and weaknesses of the presented algorithms. / I och med att fler och fler system och enheter blir utrustade med olika grader av intelligens så växer både förekomsten och omfattningen av sammankopplade system, även kallat Multi-Agent Systems. Sådana system kan vi se exempel på i traffikledningssystem, styrning av elektriska nätverk och fordonståg, vi kan också hitta fler och fler exempel på så kallade sensornätverk i och med att Internet of Things och Industry 4.0 används och utvecklas mer och mer. Det som särskiljer sammankopplade system från mer traditionella system med flera olika styrsignaler och utsignaler är att dem sammankopplade systemen inte styrs från en central styrenhet. Istället styrs dem sammankopplade systemen på ett distribuerat sätt i och med att varje agent styr sig själv och kan även ha individuella mål som den försöker uppfylla. Det här gör att analysen av sammankopplade system försvåras, men tidigare forskning har hittat olika regler och förhållninssätt för agenterna och deras sammankoppling för att uppfylla olika krav, såsom stabilitet och robusthet. Men även om dem sammankopplade systemen är både robusta och stabila så kan dem ha egenskaper som vi vill kunna kontrollera ytterligare. Specifikt kan ett sådant prestandamått vara systemens motståndskraft mot påverkan av yttre störningar och i vanliga olänkade system finns det en inneboende avvägning mellan kostnad på styrsignaler och resiliens mot yttre störningar. Samma avvägning hittar vi i sammankopplade system, men i dessa system hittar vi också ytterligare en dimension på detta problem. I och med att ett visst mått av en nätverksprestanda inte nödvändigtvis betyder att varje agent i nätverket delar samma mått kan agenterna i ett nätverk ha olika utväxling mellan styrsignalskostnad och resiliens mot yttre störningar. Detta gör att vissa agenter kan ha onödigt höga styrsignalskonstander, i den mening att systemen skulle uppnå samma nätverksprestanda men med lägre styrsignalskostnad om flera av agenterna skulle vikta om sina kontrollinsatser. I det här examensarbetet har vi studerat hur olika val av kontrollinsats påverkar ett sammankopplat systems prestanda. Vi har gjort detta för att undersöka hur autonoma, men sammankopplade, agenter kan ändra sin kontrollinsats, men med bibehållen nätverksprestanda, och på det sättet minska sina kontrollkostnader. Detta har bland annat resulterat i en distruberad algoritm för att manipulera agenternas kontrollinsats så att skillnaderna mellan agenternas resiliens mot yttre störningar minskar och nätverksprestandan ökar. Vi avslutar rapporten med att visa ett par exempel på hur system anpassade med hjälp av den framtagna algoritmen får ökad prestanda. Avslutningsvis följer en diskussion kring hur vissa antaganden kring systemstruktur kan släppas upp, samt kring vilka områden framtida forskning skulle kunna fortsätta med.